Conventionally, in an exhaust gas purifying device applied to a diesel engine or the like, there has been a technique that a diesel particulate filter (or an NOx catalyst) or the like is provided in an exhaust gas discharge route of the diesel engine mounted to a traveling machine body or the like, and the exhaust gas discharged out of the diesel engine is purified by the diesel particulate filter (or the NOx catalyst) or the like (Patent Document 1, Patent Document 2, and Patent Document 3). Further, there has been known a technique in which a filter case (an inner case) is provided within a casing (an outer case), and a particulate filter is arranged within the filter case (see Patent Document 4).